Low energy or minimum disturbance method for measuring frequency response functions of ultrasonic surgical devices in determining optimum operating point

ABSTRACT

An ultrasonic system is provided that includes an ultrasonic device having an elongated member configured to impart ultrasonic energy to tissue and a resonator configured to impart a frequency to the elongated member. The system also includes an ultrasonic generator configured to supply power to the resonator of the ultrasonic device. The ultrasonic generator has a drive signal generator configured to provide a drive signal, a noise signal generator configure to provide a noise signal, and a controller. The controller receives an output signal from the ultrasonic device and the noise signal from the noise signal generator, calculates a transfer function based on the output signal and the noise signal, and adjusts the drive signal generator based on the calculated transfer function.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 12/561,067 filed on Sep. 16, 2009, now U.S. Pat.No. 8,207,651, the entire contents of which is incorporated by referenceherein.

BACKGROUND

1. Technical Field

The present disclosure relates to an ultrasonic surgical system. Moreparticularly, but not exclusively, it relates to an ultrasonic surgicalsystem able to achieve precise control of a desired operating point.

2. Background of Related Art

Devices which effectively utilize ultrasonic energy for a variety ofapplications are well-known in a number of diverse arts. A laparoscopictool where the surgeon may use a scissors-type, a pistol or trigger typegrip outside the body to operate a manipulative, gripping or clampingmechanism at a distal end of the tool within the body is useful for usewith ultrasonically operated haemostatic cutting tools. Such haemostaticcutting tools are known from British Patent Number 2333709B,International Patent Applications Numbers PCT/GB99/00162 andPCT/GBOO/01580, and U.S. Pat. No. 5,322,055.

Each of the above identified patents and patent applications describes asurgical tool comprising means to generate ultrasonic vibrations and awaveguide, operatively connected at a proximal end to said generatingmeans, and provided at a distal end with cutting and/or coagulatingmeans. Each tool is provided with a jaw to hold tissue to be treated incontact with the ultrasonically vibrating cutting and/or coagulatingmeans.

The Ampulla (Gaussian) profile was published by Kleesattel (as early as1962), and is employed as a basis for many ultrasonic devices insurgical applications including devices patented and commercialized byCavitron and Valleylab (patents by Wuchinich, et al., 1977, Stoddard, etal., 2001) for use in ultrasonic aspiration. The Gaussian profile isused in practice to establish and control the resonance and mechanicalgain of devices. A resonator, a connecting body and the device acttogether as a three-body system to provide a mechanical gain, which isdefined as the ratio of output stroke amplitude of the radiating tip tothe input amplitude of the resonator. The mechanical gain is the resultof the strain induced in the materials of which the resonator, theconnecting body and the ultrasonic device are composed.

The magnetostrictive transducer coupled with the connecting bodyfunctions as the first stage of the booster device with a mechanicalgain of about 2:1, due to the reduction in area ratio of the wall of thecomplex geometry. The major diameter of the device transitions to thelarge diameter of the Gaussian in a stepped device geometry with a gainof as large as about 5:1, again due to reduction in area ratio. Themechanical gain increases in the Gaussian due to the Square Root of(1+2*Ln (Area Ratio)), where Ln is the natural logarithm, or about 2:1for the devices of interest. The total mechanical gain is the product ofthese constituents, or as large as 20:1 for this example. Thus, theapplication of ultrasonically vibrating surgical devices used tofragment and remove unwanted tissue with significant precision andsafety has led to the development of a number of valuable surgicalprocedures. Accordingly, the use of ultrasonic aspirators for thefragmentation and surgical removal of tissue from a body has becomeknown. Initially, the technique of surgical aspiration was applied forthe fragmentation and removal of cataract tissue. Later, such techniqueswere applied with significant success to neurosurgery and other surgicalspecialties where the application of ultrasonic technology through ahandheld device for selectively removing tissue on a layer-by-layerbasis with precise control has proven feasible.

Certain devices known in the art characteristically produce continuousvibrations having substantially constant amplitude at a predeterminedfrequency (i.e. 20-30 kHz). Certain limitations have emerged in attemptsto use such devices in a broad spectrum of surgical procedures. Forexample, the action of a continuously vibrating tip may not have adesired effect in breaking up certain types of body tissue, bone, etc.Because the ultrasonic frequency is limited by the physicalcharacteristics of the handheld device, only the motion available at thetip provides the needed motion to break up a particular tissue. Allinteraction with the tissue is at the tip, some being purely mechanicaland some being ultrasonic. The devices may have limitations infragmenting some tissues. The limited focus of such a device may renderit ineffective for certain applications due to the vibrations which maybe provided by the handheld device. For certain medical procedures, itmay be necessary to use multiple hand held devices or it may benecessary to use the same console for powering different handhelddevices.

Certain devices known in the art characteristically produce continuousvibrations having a substantially constant amplitude at a frequency ofabout twenty to about thirty kHz up to about forty to about fifty kHz.The amplitude is inversely proportional to frequency and directlyproportional to wavelength because the higher frequency transducersgenerally have less powerful resonators. For example, U.S. Pat. Nos.4,063,557, 4,223,676 and 4,425,115 disclose devices suitable for theremoval of soft tissue which are particularly adapted for removinghighly compliant elastic tissue mixed with blood. Such devices areadapted to be continuously operated when the surgeon wishes to fragmentand remove tissue.

A known instrument for the ultrasonic fragmentation of tissue at anoperation site and aspiration of the tissue particles and fluid awayfrom the site is the CUSA™ 200 System Ultrasonic Aspirator; see alsoU.S. Pat. No. 4,827,911, now sold as the CUSA Excel™. When thelongitudinally vibrating tip in such an aspirator is brought intocontact with tissue, it gently, selectively and precisely fragments andremoves the tissue. Depending on the reserve power of the transducer,the CUSA transducer amplitude can be adjusted independently of thefrequency. In simple harmonic motion devices, the frequency isindependent of amplitude. Advantages of this unique surgical instrumentinclude minimal damage to healthy tissue in a tumor removal procedure,skeletoning of blood vessels, prompt healing of tissue, minimal heatingor tearing of margins of surrounding tissue, minimal pulling of healthytissue, and excellent tactile feedback for selectively controlled tissuefragmentation and removal.

In many surgical procedures where ultrasonic fragmentation instrumentsare employed, additional instruments are required for tissue cutting andhemostasis at the operation site. For example, hemostasis is needed indesiccation techniques for deep coagulation to dry out large volumes oftissue and also in fulguration techniques for spray coagulation to dryout the surface of tissues.

The apparatus disclosed in U.S. Pat. Nos. 4,931,047 and 5,015,227provide hemostasis in combination with an ultrasonically vibratingsurgical fragmentation instrument and aspirator. The apparatuseffectively provide both a coagulation capability and an enhancedability to fragment and aspirate tissue in a manner which reduces traumato surrounding tissue.

U.S. Pat. No. 4,750,488 and its two continuation Patents, U.S. Pat. Nos.4,750,901 and 4,922,902, disclose methods and apparatus which utilize acombination of ultrasonic fragmentation, aspiration and cauterization.

In U.S. Pat. No. 5,462,522, there is disclosed, an ultrasonictherapeutic apparatus. The apparatus includes a water supply unit forsupplying cooling water to cool the probe; a suction unit for removingwaste matter by suction from the organic tissue treated by means of thecooling water and the probe; an ultrasonic output setting section forsetting a preset value for an ultrasonic output from the ultrasonicvibrator; a feedwater output setting section for setting a preset valuefor a feedwater output from the water supply unit; and a feedwateroutput control section for controlling the feedwater output setting bythe feedwater output setting section so that the preset feedwater outputvalue is a value such that the probe is cooled and is not excessivelyheated.

In U.S. Published Application 2009/0143805 A1, there is disclosed,cutting instruments that utilize ultrasonic waves generate vibrationswith an ultrasonic transducer along a longitudinal axis of a cuttingblade. By placing a resonant wave along the length of the blade,high-speed longitudinal mechanical movement is produced at the end ofthe blade. These instruments are advantageous because the mechanicalvibrations transmitted to the end of the blade are very effective atcutting organic tissue and, simultaneously, coagulate the tissue usingthe heat energy produced by the ultrasonic frequencies. Such instrumentsare particularly well suited for use in minimally invasive procedures,such as endoscopic or laparoscopic procedures, where the blade is passedthrough a trocar to reach the surgical site.

In an apparatus which fragments, cuts or coagulate tissue by theultrasonic vibration of a tool tip, it is desirable, for optimumefficiency and energy utilization, that the transducer which providesthe ultrasonic vibration operate at resonant frequency. The transducerdesign establishes the resonant frequency of the system, while thegenerator tracks the resonant frequency. The generator produces theelectrical driving signal to vibrate the transducer at resonantfrequency. However, changes in operational parameters, such as, changesin temperature, thermal expansion and load impedance, result indeviations in the resonant frequency.

More specifically, as the temperature increases, the material densitydecreases and the speed of sound increases. The increase in temperaturemay lead to a lower equivalent mass of the key system components,especially the device which has a very low mass and can heat up and cooldown quickly. The lower equivalent mass may lead to a change inequivalent resonant frequency. Additionally, when the water supply unitsupplies water to cool down the device, the water adds mass to thedevice as well as acting as a coolant to maintain the temperature of thedevice. As such, the presence of water may change the equivalentresonant frequency.

SUMMARY

The present disclosure relates to an ultrasonic system that includes anultrasonic device configured to impart ultrasonic energy to tissue. Thesystem also includes an ultrasonic generator configured to supply powerto the ultrasonic device. The ultrasonic generator has a controllabledrive signal generator as part of a negative feedback loop configured toprovide a drive signal, a controllable noise signal generator configureto provide a noise signal, and a controller. The controller receives anoutput signal from the ultrasonic device and the noise signal from thenoise signal generator, calculates a transfer function estimate based onthe output signal and the noise signal, and adjusts the drive signalgenerator based on the calculated transfer function estimate.

In another embodiment according to the present disclosure, an ultrasonicgenerator configured to supply power to an ultrasonic device isprovided. The ultrasonic generator has a drive signal generatorconfigured to provide a drive signal, a noise signal generatorconfigured to provide a noise signal, and an adder configured to combinethe drive signal and the noise signal. The ultrasonic generator alsoincludes an amplifier having a gain configured to amplify the combinedsignal. A controller is configured to receive an output signal from theultrasonic device and the noise signal from the noise signal generator,calculate a transfer function estimate based on the output signal, thenoise signal and the gain, and adjust the drive signal generator basedon the calculated transfer function estimate.

In yet another embodiment according to the present disclosure, anultrasonic generator configured to supply power to an ultrasonic deviceis provided. The ultrasonic generator has a drive signal generatorconfigured to provide a drive signal, an amplifier having a gainconfigured to amplify the drive signal, a noise signal generatorconfigured to provide a noise signal, and a resonance circuit configuredto provide an output to the resonator of the ultrasonic device. Theultrasonic generator also includes a transformer having a first primarywinding coupled to the amplifier, a second primary winding coupled tothe noise signal generator and a secondary winding coupled to theresonance circuit. A controller is also provided that is configured toreceive an output signal from the ultrasonic device and the noise signalfrom the noise signal generator, calculate a transfer function estimatebased on the output signal and the noise signal, and adjust the drivesignal generator based on the calculated transfer function estimate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view of an ultrasonic device in accordance withan embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of a part of the handset of the tool ofFIG. 1 including a turning element;

FIG. 3 is a perspective view of an ultrasonic device in accordance withan embodiment of the present disclosure;

FIG. 4 is an enlarged view of a tip of the ultrasonic device of FIG. 3;

FIG. 5 is a top view of the ultrasonic device of FIG. 3 with a channelshown in phantom;

FIG. 6 is a side view of the ultrasonic device of FIG. 3;

FIG. 7 is a cross-sectional view of the ultrasonic surgical device ofFIG. 5;

FIG. 8 is a cross-sectional view of the ultrasonic surgical device ofFIG. 6;

FIG. 9 is a side elevational view of an exemplary handle with theleft-side shell removed in accordance with an embodiment of the presentdisclosure;

FIG. 10 is a perspective view from the front left side of a hand-heldultrasonic cutting pen device in accordance with an embodiment of thepresent disclosure;

FIG. 11 is a side elevational view of the hand-held ultrasonic cuttingpen device of FIG. 10 from the left side;

FIG. 12 is a side elevational view of the hand-held ultrasonic cuttingpen device of FIG. 11 with the left-side shell removed;

FIG. 13 is a diagrammatic illustration of a hand-held ultrasonic cuttingpen device to be connected to a man-portable, control and power supplyassembly in accordance with an embodiment of the present disclosure;

FIG. 14 is a perspective view of a hand-held ultrasonic cutting pendevice to be connected to a man-portable, control and power supplyassembly in accordance with an embodiment of the present disclosure;

FIG. 15 is a perspective view of the hand-held ultrasonic cutting pendevice of FIG. 15 with a left-half shell removed;

FIG. 16 is a perspective view of a portable, control and power supplyassembly to be connected to a hand-held ultrasonic cutting pen device inaccordance with an embodiment of the present disclosure;

FIG. 17 is a schematic of an ultrasonic generator in accordance with anembodiment of the present disclosure; and

FIG. 18 is a schematic of an ultrasonic generator in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure will be describedhereinbelow with reference to the accompanying drawings; however, it isto be understood that the disclosed embodiments are merely exemplary ofthe disclosure, which may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

Embodiments of the presently disclosed ultrasonic surgical system aredescribed in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As used herein, the term “distal” refers to thatportion of the instrument, or component thereof which is further fromthe user while the term “proximal” refers to that portion of theinstrument or component thereof which is closer to the user.

Referring now to the drawings and to FIG. 1 in particular, a surgicaltool, in this case an ultrasonic surgical haemostatic tool, comprises anelongate waveguide 1 for ultrasonic vibrations (torsional modeultrasonic vibrations are preferred, although longitudinal modeultrasonic vibrations may also be utilized). An example of such anultrasonic surgical device is disclosed in U.S. Pat. No. 7,520,865 toYoung et al. currently owned by and assigned to Covidien AG, the entirecontents of which are incorporated herein by reference. The waveguide 1defines a longitudinal axis of the tool, as shown by dotted line 2-2. Aproximal end 1 a of the waveguide 1 is mounted to an ultrasonicvibration generator 20 which will be described in more detailhereinbelow.

The waveguide 1 is disposed coaxially within an elongate carrier tube 3,which is mounted at its proximal end to a cylindrical turning element 4.The carrier tube 3 and the turning element 4 are rotatable as a unitabout the longitudinal axis 2, in the sense of arrows 5. The turningelement 4 is acted on by a trigger mechanism or other manual operatingmeans, as detailed below. A jaw member 6 is mounted pivotably to adistal end 3 b of the carrier tube 3.

A plurality of spacers (not shown) may be provided between the waveguide1 and an inner wall of the carrier tube 3, insulating the carrier tube 3from ultrasonic vibrations transmitted by the waveguide 1 andmaintaining their relative disposition.

An outer tube 7 is disposed coaxially around the carrier tube 3 and thewaveguide 1. The outer tube 7 is mounted at its proximal end to amounting block 8, which is mounted non-rotatably to a handset of thetool (not shown in this Figure). At its distal end, the outer tube 7 isprovided with a guide lobe 9, which bears on a rearward facing contactsurface 10 of the jaw member 6. The turning element 4 and the mountingblock 8 are biased apart, for example with a spring, other resilientdevice, or cam means such that the guide lobe 9 and the contact surface10 remain co-operatingly in contact one with another.

When the carrier tube 3 is rotated, the contact surface 10 of the jawmember 6 mounted thereto moves across the guide lobe 9 of the stationaryouter tube 7, thereby causing a pivoting movement of the jaw member 6away from or towards contact with the distal end 16 of the waveguide 1,as detailed below.

The outer tube 7 also acts as a protective sheath for the greater partof the rotatable carrier tube 3 and the waveguide 1, for exampleprotecting them from body fluids as far as possible. In a preferredembodiment of the tool, the carrier tube 3 and the outer tube 7 aredetachable from the handset of the tool. The carrier tube 3 and the jawmember 6 that it carries may then be withdrawn in a distal directionfrom the outer tube 7, so that each may be cleaned and sterilizedseparately before re-use, or alternatively so that either or both may bedisposed of and replaced with a fresh equivalent.

FIG. 2 shows a part of the handset of the tool, together with proximalportions of the outer tube 7 and the carrier tube 3. The mounting block8 is mounted, permanently or removably, to a handset casing 11. In thisparticular embodiment of the tool, the turning element 4 is providedwith a part helical slot 12 in its cylindrical wall, which is adapted toreceive a driving stud (not shown) mounted to a trigger mechanism (notshown) which extends out of the casing 11 through an aperture 13provided therefor. The trigger mechanism may optionally be mounted to apivot mounting 14 on the casing 11, as shown, or to a pivot mountingdisposed adjacent the aperture 13. Pivoting movement of the triggermechanism, which is configured to be grasped by a hand of a user, movesthe driving stud in a generally longitudinal direction. As the drivingstud is constrained to move within the part helical slot 12, a forwardmotion of the stud causes the turning element 4, and hence the carriertube 3, to rotate in an anticlockwise sense (viewed from a proximal endof the tool) and a rearward motion of the stud causes the turningelement 4 and the carrier tube 3 to rotate in a clockwise sense.

The ultrasonic vibration generator is conveniently mounted inside adetachable element of the casing 11. FIG. 2 shows the handset with thatelement detached, and the waveguide 1, mounted to the ultrasonicgenerator, thereby withdrawn from its operating disposition disposedcoaxially within the carrier tube 3.

An ultrasonic device 100, in accordance with one embodiment of thepresent disclosure, is illustrated in FIG. 3. Ultrasonic device 100 isadapted for use in an ultrasonic surgical system having an ultrasonichandpiece. An example of such an ultrasonic surgical system is disclosedin U.S. Pat. No. 6,214,017 to Stoddard et al. currently owned by andassigned to Sherwood Services AG, the entire contents of which areincorporated herein by reference. Alternatively, ultrasonic device 100may be adapted for use with the ultrasonic surgical system disclosed inU.S. Pat. No. 4,063,557 to Wuchinich et al., the entire contents ofwhich are incorporated herein by reference.

Referring to FIGS. 3 and 4, in one embodiment of the present disclosure,ultrasonic device 100 includes an adapter 130 having a first or proximalend 172 and a second or distal end 174. Extending from proximal end 172,adapter 130 includes a fillet 132, a nut 134 and a flange 136terminating at distal end 174. Flange 136 includes a leading edge 138.Proximal end 172 of adapter 130 is configured to connect ultrasonicdevice 100 to an ultrasonic handpiece or resonator 150 via a connectingportion 140. Connecting portion 140 is capable of coupling ultrasonicdevice 100 and connecting portion 140 to ultrasonic handpiece orresonator 150. As used herein, the term “resonator” is used to refer towhat is often referred to in the literature as an ultrasonic handpiece.Ultrasonic device 100 includes an elongated member 110 having a first orproximal end which coincides with distal end 174 of adapter 130.Elongated member 110 has a second or distal end 180, and distal end 174of adapter 130 is joined, in one embodiment unitarily, to the coincidingproximal end of elongated member 110. Distal end 180 of elongated member110 is configured as a tip lead 120. Tip lead 120 extends from a firstor proximal end, as is discussed in more detail below.

Connecting portion 140 includes a first or proximal end 142 which isconfigured to connect to a resonator 150 at a distal end thereof.Resonator 150 includes, in one embodiment, a magnetostrictivetransducer, although other transducer types can be included such as apiezoelectric transducer. Resonator 150 is supplied power fromultrasonic generator 200 (described in more detail below) such thatresonator 150 operates at a desired frequency. In one embodiment,ultrasonic device 100 is made of titanium, although other materials suchas stainless steel can be used.

As seen in FIG. 5, an internal channel 160 is formed within elongatedmember 110. As is known in the art, the channel terminates in theconnecting body, and does not continue in the resonator. The resonatoris typically a laminated core-stack of Permanickel. In mostimplementations, the central channel supports aspiration suction oftissue. The channel also affords greater mechanical gain because thegain is dependent on the reduction in area ratio of the thin walls. Theprimary purpose of the channel is to support gain for bone tips with thechisel/awl distal ends. The internal channels of the bone abrading tipsin the disclosure shown and described below would also aid in cooling,where irrigation liquid is suctioned via the internal diameter channel.Surgical procedures on bone typically employ an auxiliary suction tubeto remove the larger volumes of irrigation liquid and bone debris.

Referring to FIGS. 5-6, FIG. 8 is a top view of ultrasonic device 100 ofFIG. 3 with channel 160 shown in phantom formed within elongated member110. FIG. 6 is a side view of ultrasonic device 100 of FIG. 3 withchannel 160 in phantom formed within elongated member 110. FIG. 7 is across-sectional view of ultrasonic surgical device 100 of FIG. 5 showingchannel 160 formed within elongated member 110. FIG. 8 is across-sectional view of ultrasonic surgical device 100 of FIG. 6 againshowing channel 160 formed within elongated member 110. Internal channel160 is formed within adapter 130 and elongated member 110 of ultrasonicdevice 100.

Elongated member 110 is tapered such that the cross-sectional area is amaximum at proximal end 174 interfacing with adapter 130 and is aminimum at proximal end 178 of tip lead 120. Channel 160 is asubstantially constant diameter central hole of diameter d₁ formedwithin elongated member 110 to enable enhanced mechanical gain in device100. In the case of a device with a channel, it is the area ratio of thecross-sectional area based on the outer diameter of the elongated member110 near the leading edge 138 of flange 136 versus the cross-sectionalarea based on the outer diameter of the elongated member 110 at thedistal end 176. The area ratio along the length L of the device isdecreased towards tip lead 120 at the distal end of elongated member110, and velocity and elongation of the titanium particles areincreased. The ultrasonic wave is supported by particle motion in thetitanium. The particles vibrate about their neutral position in alongitudinal or extensional wave. The particles do not move along thelength of the device, but only vibrate, just as a cork or bobber showsthat a wave passes through water via the liquid. As the device wallthickness decreases, more strain occurs in the metal as the particlesmove a greater distance about their neutral position. The displacementof the end of the device is due to strain along the device. All theparticles supporting the wave are moving at the same resonant frequency.The greater the strain, the greater the velocity of the particlesnecessary to maintain the same frequency.

As best illustrated in FIG. 4, distal end 180 of tip lead 120 has asemi-circular planar surface configuration 122, such that distal end 180of ultrasonic device 100 is in the form of a chisel and an awl. (Awlsare utilized in manual boring of holes, such as in boring leather orwood). Tip 180 of ultrasonic device 100 is blunt or dull. The boring ofholes with device 100 is better facilitated with slightly semi-circularmanual motion; however plunge cuts in bone and wood have beenaccomplished with just longitudinal motion of device 100. Thecombination of the chisel and awl distal end 180 of device 100 supportsdefined cutting or abrasion of sections, planes, notches, grooves, andholes in bone. Channel or central hole 160 extends from proximal end 172of adapter 130 to approximately distal end 176 which coincides withproximal end of solid portion 114 of elongated member 110.

Another example of an ultrasonic surgical device is disclosed in UnitedStates Published Application Number 20090143805 to Palmer et al.currently owned by and assigned to Syntheon, LLC, the entire contents ofwhich are incorporated herein by reference. Referring now to FIG. 9, anultrasonic surgical device 900 in accordance with an embodiment of thepresent disclosure is depicted. When an ultrasonic-movement-generationassembly 902 is coupled to a handle 914, the transducer 916 is caused tobe releasably physically coupled to a waveguide 904, 908 through thetransducer attachment port 918 and waveguide attachment port 920. It isenvisioned that the transducer assembly 916 can be temporarily lockedinto a fixed rotational position so that the waveguide 904 can beattached to the threads (not shown) with sufficient force. This physicalcoupling between the waveguide 904 and the transducer assembly 916allows the transducer assembly 916 to impart movement to the waveguide904 when power is applied to the transducer assembly 916.

The device 900 has a spindle 906 that attaches to the waveguide 908. Thespindle 906 has indentions that allow a surgeon to easily rotate thespindle 906 and, therefore, the attached waveguide 908 and transducerassembly 916 that is attached to the waveguide 908. Such a configurationis useful for obtaining the proper cutting-blade angle during surgery.To provide for this rotation, in one embodiment, the transducer assembly916 is able to rotate freely within the transducer housing 910.

During initial coupling of the transducer assembly 916 and waveguide904, all that is needed is that one of the transducer assembly 916 andthe waveguide 904 remains relatively stationary with respect to theother. According to one embodiment of the present disclosure, when thetransducer assembly 916 is located inside the housing 910 where itcannot be readily secured by the operator, for example, by holding itsteady by hand when the waveguide 908 is being secured—theultrasonic-movement-generation assembly 902 is provided with a button(not shown) that slides into a recess in the housing 910 or,alternatively, by fixing the rotation of the transducer assembly 916 ata maximum rotational angle so that, once the maximum rotation isreached, for example, 360 degrees of rotation, no additional rotation ispossible and the waveguide 904 can be screwed thereon. A maximumrotation in the opposite direction will allow the waveguide 904 to beremoved as well.

In an alternative exemplary embodiment to the gun device, FIGS. 10 to 12illustrate an entirely hand-held and fully self-contained cautery andcutting device 1000. This cutting device 1000 reduces the size of thepower supply 1002 considerably. Here, in comparison to the previousembodiments, the waveguide 1004 is reduced in length. The ultrasonicgenerator and the power supply 1002 reside at the handpiece 1010. As inthe other embodiments described above, the pen shaped device shown inFIGS. 10 to 12 could have, in accordance with one embodiment, a sealedbody 1002, where the body 1002 housing the ultrasonic generator and thepower supply 1002 is autoclavable and the waveguide 1004 is simplyreplaced for each procedure.

FIG. 13 depicts another shape for the cautery/cutting device 1300 thatis shaped to fit into a surgeon's hand for ease of use. Another shapefor the pen device 1500 is shown in FIGS. 14 and 15 and is similar to awriting pen so that the surgery can be carried out with the device 1500to approximate writing—a process that is comfortable to most physicians.The pen 1300, 1500 includes all of the transducer components—thetransducer 1302, 1502, the protective cannula 1304, 1504, and thewaveguide 1306, 1506.

In these embodiments, the base 1600, shown in FIG. 16, has a body 1606that houses a self-contained power source (i.e., a battery) and agenerator circuit operable to generate an output waveform and is sizedto be handheld. The base 1600 is connected through a communications andpower tether cord 1602, illustrated diagrammatically in the figures witha dashed line, to the pen-shaped ultrasonic waveguide handle 1500, shownin FIGS. 15-16. When in operation, the transducer 1502 within the handle1500 is driven by a plurality of driving waves output from the waveformgenerator within the body 1506.

The base 1600 has a user interface 1604 that can be used to communicatedata and carry out functions of the device, such as testing andoperation. Through the user interface 1604, the device can be tested inthe sealed package without even opening the package. For instance, inone embodiment, a user can press one or more non-illustrated buttons(physical or electronic) in a given sequence (e.g., 5 times in a row)and, thereby, cause the user interface 1604 to display a status of thebattery and/or a status of the logic circuitry, all without having toremove it from the sealed package. This is helpful in case of a defect,such as a bad battery, as the purchaser would be able to return thedevice to the manufacturer before use and, thereby, prove non-use of thedevice to receive credit. In this embodiment, all of the ultrasonicgenerator components reside in the base 1600.

The base 1600 is also provided with a non-illustrated clothingattachment mechanism that can be a simple belt clip, or any other way ofattaching a device to a wearer. The clothing attachment mechanism allowsa surgeon or nurse to wear the base 1600 during a surgery so that thecord 1602 will always be of sufficient length, i.e., as long as his armcan reach, no matter where the surgeon is standing.

Referring to FIG. 17, an apparatus or ultrasonic generator 1700 isprovided which is configured to supply power to the resonator 150.Ultrasonic generator 1700 uses a negative feedback loop to control theoutput of the ultrasonic generator 1700. Ultrasonic generator 1700includes a controllable drive signal generator 1702 that generates adrive signal (A_(ds)) to control the ultrasonic device. The drive signalgenerator 1702 outputs a sine wave in an embodiment of the presentdisclosure. The sine wave may also be substituted with a square wave,triangular wave or a pulse width modulated (PWM) form of the sine wave.Noise generator 1704 is also provided which outputs a controllable noisesignal (A_(ns)). The ultrasonic device tends to self heat which wouldincrease resonance. Alternatively, the added load at the distal tip ofthe device will add mass and/or compliance, which will also change theresonance. The resonance changes quickly as the ultrasonic device coolsagain or is transiently loaded and unloaded. By adding a noise signalsuch as a “pink” noise or narrowband white noise, with many Fast FourierTransform (FFT) bins averaged together, an operating point can bedetermined and the ultrasonic device could be tuned to the operatingpoint. A FFT is an efficient algorithm to compute the discrete Fouriertransform (DFT) and its inverse. A DFT decomposes a sequence of valuesinto components of different frequencies. This operation is useful inmany fields but computing it directly from the definition is often tooslow to be practical. An FFT is a way to compute the same result morequickly: computing a DFT of N points in the obvious way, using thedefinition, takes O(N²) arithmetical operations, while an FFT cancompute the same result in only O(N log N) operations. The difference inspeed can be substantial, especially for long data sets where N may bein the thousands or millions—in practice, the computation time can bereduced by several orders of magnitude in such cases, and theimprovement is roughly proportional to N/log(N).

In another embodiment of the present disclosure, a pseudo random noisesequence (PRNS) may be provided as a noise signal by noise signalgenerator 1704. Using a PRNS noise signal allows the ultrasonic systemto determine the phase of an output signal with respect to the inputsignal.

The drive signal and noise signal are combined (A_(dns)) by adder 1706and the combined signal is provided to amplifier 1708. Amplifier 1708has a gain “k” which can be a predetermined value set by themanufacturer or could be adjusted by a user of the ultrasonic system.The output of amplifier 1708 is provided to the ultrasonic device 100 asdescribed above. Ultrasonic device has a transfer function “G” thatdetermines the resonance and electro-mechanical gain of the device asdescribed above. Ultrasonic device outputs an ultrasonic signal(A_(out)) proportional to the stroke or mechanical force produced by theultrasonic device that is to be controlled by the negative feedbackloop.

As shown in FIG. 17, the ultrasonic signal is provided to a controller1710. Controller 1710 also receives or has a priori information on thestatistics of the noise signal from noise signal generator 1704, thedrive signal from drive signal generator 1702, and the gain “k” fromamplifier 1708. Controller 1710 may be any available processor or logiccircuit configured to perform the functions described below. Controller1710 may also include a memory configured to store predetermined ormeasured parameters to use in the controller's 1710 operations. Althoughnot shown, controller 1710 may be coupled to an input device, such as akeypad, keyboard, mouse, touch screen, scanner, or the like. Controller1710 may also be coupled to an output device such as any type of displaythat provides a visual indication such as a monitor, light emittingdiode display, liquid crystal display, printer, or the like.

Because the increase in temperature may lead to a lower equivalent massof the key ultrasonic system components (for instance, in oneembodiment, the water supply unit supplies water to cool down the devicewhere the water adds mass to the device as well as acting as a coolantto maintain the temperature of the device), the equivalent resonantfrequency of the ultrasonic device may change. Accordingly, controller1710 applies a transfer function using the FFT's of the ultrasonicsignal output and the noise signal from noise signal generator 1704.More specifically, the controller 1710 calculates the new transferfunction estimate “Ĝ” of the ultrasonic device by dividing the averageof the output power FFT's |A_(out)|² by the input FFT's noise power|A_(ns)|² and gain “k”. The controller 1710 can also determine the phasedifference between the output power signal and the combined signal bytime aligning the noise signal from noise signal generator 1704 and thenoise signal in the output power signal. The phase difference may alsobe determined using a phase-locked loop (PLL) circuit (not shown). Basedon the new transfer function estimate “Ĝ”, a new equivalent resonancefrequency can be determined. Drive signal generator 1702 is adjusted bythe controller 1710 to provide a new drive signal based on the newequivalent resonance frequency.

FIG. 18 depicts another embodiment of an ultrasonic generator 1800 inaccordance with the present disclosure. As shown in FIG. 18, a drivesignal generator 1802 provides a drive signal to amplifier 1804.Amplifier 1804 may be a non-linear amplifier such as Class D amplifier.A Class D amplifier is an electronic amplifier which, in contrast to theactive resistance used in linear mode AB-class amplifiers, uses theswitching mode of transistors to regulate power delivery. The amplifier,therefore, features high power efficiency (low energy losses), whichadditionally results in lower weight by eliminating bulky heat sinks.Additionally, if voltage conversion is necessary, the on-the-way highswitching frequency allows the bulky audio transformers to be replacedby small inductors. Low pass LC-filtering smoothes the pulses out andrestores the signal shape on the load.

The output of amplifier 1804 is provided to an inductor L1 which iscoupled to a primary winding 1812 of a transformer 1810. Unlike theembodiment described in FIG. 17, the ultrasonic generator 1800 providesa noise signal generator 1806 after the amplifier 1804. The noise sourceis coupled to a winding on the primary side 1814 of transformer 1815.The secondary winding of 1811 of transformer 1815 is coupled to primarywinding 1812 of transformer 1810. The secondary winding 1816 oftransformer 1810 is coupled to an LC circuit or resonance circuit 1820which then provides an output of both the drive signal and the noisesignal to a resonator such as resonator 150 of ultrasonic device 100described hereinabove. An LC circuit is a resonant circuit or tunedcircuit that consists of an inductor, represented by the letter L, and acapacitor, represented by the letter C. When connected together, anelectric current can alternate between them at the circuit's resonantfrequency. The LC circuit is typically used to compensate for losses inthe class D amplifier that may occur due to complex loading effects ofthe ultrasonic device.

Similar to ultrasonic generator 1700, the output of the ultrasonicdevice is provided to a controller 1830 which calculates the newtransfer function estimate “Ĝ” of the ultrasonic device by dividing theaverage of the output power FFT's |A_(out)|² by the input FFT's noisepower |A_(ns)|². The controller 1830 can also determine the phasedifference between the output power signal and the combined signal by“time aligning” the noise signal from noise signal generator 1806 andthe noise signal in the output power signal. Based on the new transferfunction estimate “Ĝ”, a new equivalent resonance frequency can bedetermined. Drive signal generator 1802 is adjusted by the controller1830 to provide a new drive signal based on the new equivalent resonancefrequency.

The described embodiments of the present disclosure are intended to beillustrative rather than restrictive, and are not intended to representevery embodiment of the present disclosure. Various modifications andvariations can be made without departing from the spirit or scope of thedisclosure as set forth in the following claims both literally and inequivalents recognized in law.

1. An ultrasonic system, comprising: an ultrasonic device configured toimpart ultrasonic energy to tissue; and an ultrasonic generatorconfigured to supply power to the ultrasonic device, the ultrasonicgenerator comprising: a controllable drive signal generator configuredto provide a drive signal; a controllable noise signal generatorconfigured to provide a noise signal, wherein the noise signal is apseudo random noise sequence; an adder configured to combine the drivesignal and the noise signal; an amplifier having a gain, the amplifierconfigured to amplify the combined drive signal and noise signal andprovide the amplified signal to the ultrasonic device; and a controllerconfigured to: receive an output signal from the ultrasonic device andthe noise signal from the noise signal generator, calculate a transferfunction estimate based on the output signal and the noise signal,adjust the drive signal generator based on the calculated transferfunction estimate, and determine a phase difference by time aligning anoise signal in the output signal with the noise signal provided by thenoise generator.
 2. The ultrasonic system according to claim 1, whereinthe controller uses the gain of the amplifier to calculate the transferfunction estimate.
 3. The ultrasonic system according to claim 1,wherein the noise signal is pink noise.
 4. The ultrasonic systemaccording to claim 1, wherein the noise signal is a narrowband whitenoise.
 5. The ultrasonic system according to claim 1, wherein the gainis predetermined by a manufacturer.
 6. The ultrasonic system accordingto claim 1, wherein the gain is set by a user.
 7. The ultrasonic systemaccording to claim 1, wherein the controller calculates a Fast FourierTransform of the output signal and the noise signal to calculate thetransfer function estimate.
 8. An ultrasonic generator configured tosupply power to an ultrasonic device, the ultrasonic generatorcomprising: a drive signal generator configured to provide a drivesignal; a noise signal generator configure to provide a noise signal; anadder configured to combine the drive signal and the noise signal; anamplifier having a gain configured to amplify the combined signal; and acontroller configured to: receive an output signal from the ultrasonicdevice and the noise signal from the noise signal generator, calculate atransfer function estimate based on the output signal, the noise signaland the gain, adjust the drive signal generator based on the calculatedtransfer function estimate, and determine a phase difference by timealigning a noise signal in the output signal with the noise signalprovided by the noise generator.